In many surgical procedures, it is desirable that when joining tissue using surgical needles and sutures, that the maximum diameter of the needle; that is, the diameter at the blunt end of the needle, and the maximum diameter of the suture be as close to the same size as possible. This design is necessary so that the hole in the tissue produced by passing the needle through the tissue is substantially filled by the suture. This is especially important when joining vascular tissue to prevent oozing or seepage of blood through the hole produced by the needle.
Originally, surgical needles had an eye at the blunt end through which the suture was attached. As can be appreciated, this meant that the blunt end of the needle had sufficient size to allow for an eye to be placed in and that at least double the maximum diameter of the suture would be placed through that eye so that the hole produced when the needle was passed through tissue was substantially greater than the diameter of the suture. Over the years, to improve surgical procedures, various techniques have been developed to eliminate the eye in the blunt end of the needle and find other techniques by which the suture can be attached to the blunt end of the needle. Some of the techniques that have been developed are to place a channel in the blunt end and crimp the suture in that channel or swage the suture into a hole drilled in the blunt end of the needle. As can be appreciated, it is still required that the diameter of the blunt end of the needle be substantially larger than the diameter of the body of the suture and hence when such a needle-suture combination is used to join tissue, the suture still does not completely fill the hole formed by the needle.
In recent years, various techniques have been developed to reduce the diameter of the suture at the end that is to be attached to the blunt end of the needle and in many instances this has been accomplished so that the diameter of the body of the suture is substantially the same as the diameter of the blunt end of the needle. Some of these techniques are more fully described in U.S. Pat. Nos., 3,890,975 and 3,926,194. Though these techniques produce a needle-suture combination wherein the maximum diameter of the suture is close to the diameter of the blunt end of the needle, in order to accomplish this they all greatly reduce the strength of the suture in that area of the suture that is attached to the needle or immediately adjacent that area. This, of course, produces a weakened needle-suture combination. This problem restricts the various sizes of sutures that can be produced by these techniques especially the extremely fine size sutures. It also limits the types of materials that can be used to produce the sutures in that you must greatly increase the overall strength of the suture to have sufficient strength at the reduced diameter portion.